As temperatures rise, Antarctic wildlife on the edge of disaster

Even a small increase in sea temperatures could trigger a chain effect that would rapidly destroy a large percentage of marine life, a British scientist warns

By Tim Radford / THE GUARDIAN , London

Warmer temperatures in the Antarctic could threaten penguins, whales, seals and a host of smaller creatures, a marine biologist warns in a lecture to be given at Christmas. Lloyd Peck, of the British Antarctic Survey, argues that even a small rise in sea temperatures could have dramatic consequences.

"Antarctic animals -- in the sea especially -- are very sensitive to climate change and they are the early warning system for the loss of species on the planet. We should be watching for those because climate change is probably going to get rid of them before it gets rid of other species," he says.

"We know things are changing; it is going to be really unpleasant; we are going to lose things -- we just don't know how much," he said.

Peck, 47, a scuba diving expert on the strange fauna of the south polar seabed, will deliver this year's UK Royal Institution Christmas lecture, backed by film from Antarctica. The Christmas lectures for young people were founded by the physicist Michael Faraday in the mid-1820s and have been televised since 1966.

His message is that important species in the freezing southern seas are so sensitive to temperature shifts that they could perish in a world only a couple of degrees warmer.

"We take clams out of the sediment and let them bury themselves again. We take limpets off the seashore, turn them over and let them turn back again. If you warm them up by about two degrees or so from their normal summer temperatures, they lose the ability to do those functions," he says.

Antarctic krill, the tiny shrimp-like creatures that flourish in their billions, are also at risk. In winter, krill depend on thick mats of green algae that flourish on the underside of ice shelves which extend out of the polar darkness into the sub-Antarctic light.

As the oceans warm, the winter ice will retreat, and the algae will vanish.

"If one of the key species in the system goes, then very quickly you'd lose a lot of the system. And that would affect penguins, seals and whales. The fishery areas around the Antarctic would be affected," he said.

"So the animals that everybody is interested in -- the furry ones with big eyes, the penguins, the whales -- there is potential for them to be affected very quickly by the loss of a few species in the Antarctic food chain," Peck said.

The Antarctic continent is still cold. But the Antarctic peninsula, home to the British research bases, has warmed by up to 3?C in the last 50 years.

"We have seen big losses of ice shelves and glaciers, recession of ice, and have seen new habitable areas for animals on the Antarctic peninsula," Peck said.

"On this trip I saw grass growing in areas that I have not seen grass before. I am seeing mosses and animals on land that was covered in ice just five or 10 years ago," he said.

Seals and penguins are adapted to dramatic seasonal changes in temperature and travel huge distances for food. But polar life is unforgiving, and small cyclical shifts in temperatures in the equatorial Pacific already cause huge losses to penguin colonies further south.

"When you have low krill stocks the penguins die, and they die when the chicks get to fledgling age. The time when the chicks need food most is just when they are about to go to sea. If the food supply is not enough, you can have 95 percent or 99 percent mortalities in a couple of weeks," Peck said. "The whole place goes from a mass of penguin chicks to a big mass of dead bodies all over the place."